Precoding is a technique used in wireless transmission where multiple data streams are spatially multiplexed by an access point (AP) to a number of receiving stations (STAs) by using multiple transmit antennas. This transmission mode is sometimes referred to as downlink multi-user multiple-input and multiple-output (DL-MU-MIMO). The design of the precoder can be divided into two separate functional blocks: 1) the transmit filters, for example zero-forcing (ZF) or minimum mean-square error (MMSE), with unit norm columns and 2) the power loading. In a typical DL-MU-MIMO transmission orthogonal frequency-division multiplexing (OFDM) is used to modulate the signal across a wide bandwidth.